1. Field of the Invention
This invention relates generally to extruded composite building materials. In particular, the present invention relates to extruded lightweight composite building materials containing a high percentage of wood particles.
2. Description of Related Art
Because of the need to stop waste materials from going to landfills or being burned, the Wood Plastic Composite (WPC) market has grown. The need has been for WPCs to perform more like wood, but too many of the properties of the plastic are imparted to the WPC, and known WPC's have fallen short of this need.
Generally, known WPC's are not as lightweight, nailable, or paintable as wood and they do not have the machineability of wood.
There are several extruded WPC materials known in the art, it is also known to make lightweight foamed plastic parts. However, WPC materials and parts are typically heavier than real wood and the amount of wood present in the known WPCs is typically only 5% to 40%. Additionally, the density of most WPC materials is greater than 0.8 sq. and many WPC parts have a density of 1.1 to 1.2 sq.
Furthermore, most foamed WPC are comprised of styrene PVC, ABS or ASA.